An output driver to drive a semiconductor device such as a semiconductor memory outputs an output signal to the semiconductor memory via a transmission line. In the semiconductor memory, a terminator is provided or not provided in the line for transmitting the output signal. Characteristics required for the output driver vary depending on the presence of the terminator. That the terminator is provided or present means that a resistance or the like is connected to a far end to prevent the output signal from being reflected by the terminator of the transmission line.